FNZ 61 - Lucanidae (Insecta: Coleoptera) - Systematics
Holloway, BA 2007. Lucanidae (Insecta: Coleoptera). Fauna of New Zealand 61, 254 pages.
( ISSN 0111-5383 (print), ; no. 61. ISBN 978-0-478-09395-7 (print), ). Published 21 Nov 2007
Family Lucanidae Latreille, 1804a: 149
In the two major catalogues of Lucanidae (Roon 1910; Benesh 1960) authorship of the family is attributed to MacLeay (1819) but Lawrence & Newton (1995) have traced the first usage of Lucanidae to Latreille (1804a) and this is the citation that I am using here. It is possible that an even earlier date may be available because Latreille (1804b) stated that he had proposed the family several years before in his paper entitled “Précis des caractères génériques des Insectes” (Latreille 1796) (which I have not seen). He goes on to say that from considerations afterwards he had been compelled to reunite Lucanidae with Scarabaeidae (see Latreille 1802) but that a subsequent scrutiny brought him back to the first idea and he therefore re-established the family.
Characterisation of the family
Adult lucanids can be recognised as members of the superfamily Scarabaeoidea by the following characters (based mainly on Lawrence & Britton 1991):
- antennal club with 3–8 segments (Fig. 1);
- pronotum large (Fig. 1, 2);
- ventral portion of pronotum (hypomeron) on each side joined directly to the prosternum at the notosternal suture (Fig. 2, 50, 51), there being no visible propleuron and therefore no notopleural suture;
- fore coxae very large, transverse or conical, projecting below the prosternum and with posteriorly closed cavities (Fig. 2, 50);
- fore tibiae somewhat flattened, with 1 or more teeth on the dorsal (outer) edge, and a single apical spur (Fig. 1, 63);
- tarsi with 5 distinct segments, none of these lobed (Fig. 1).
The New Zealand lucanids are distinguished from Scarabaeidae and Trogidae, the other scarabaeoids in New Zealand, by the following combination of characters (partly from Lawrence & Britton 1991 and Klimaszewski & Watt 1997):
- head never completely concealed by the pronotum, and never with conspicuous horns nor with very large tubercles;
- mandibles well developed, extending forward horizontally beyond the frons, sexually dimorphic, those of males usually larger and more elaborately toothed than those of females;
- antennae relatively long, 10-segmented;
- antennal club segments thick, somewhat cylindrical in cross section, never leaf-like, always capable of at least some separation (Fig. 1);
- scape long, slender, clearly visible when the antenna is extended laterally;
- mid coxal cavities open laterally (Fig. 2), that is, partly closed by the mesepimera in contrast to cavities which are closed laterally by the broad meeting of the meso- and metasterna (see Klimaszewski & Watt 1997, fig. 43 for cavities which are closed laterally);
- abdomen with 5 ventrites (Fig. 2).
Lucanid larvae are typically scarabaeiform (Klimaszewski & Watt 1997, fig. 98) with a C-shaped body, a strongly sclerotised and deeply pigmented head, long antennae, and well developed legs. They differ from other scarabaeoid larvae in having a stridulatory apparatus consisting of a patch of fine asperities (the pars stridens) on the mid coxae and a row of larger asperities (the plectrum) on the hind coxae, by lacking transverse folds on the abdominal terga and in having a longitudinally oval pad on either side of the vertical anal opening. Stridulatory structures and other lucanid larval features in a range of species including some found in New Zealand are discussed and illustrated in Alderson (1975), Lawrence (1981a), and Franciscolo (1997).
Classification of the Lucanidae
Historically the classification of the family has been very controversial with from 3 subfamilies (Sharp & Muir 1912) to 10 subfamilies (Didier & Séguy 1953) being proposed, and with equal confusion about the assignment of genera to the subfamilies (Holloway 1960). A detailed study of the external morphology and male genitalia of species representing several key lucanid genera (Holloway 1960, 1968, 1969, 1972) resulted in a proposal to divide the family into 4 subfamilies, Aesalinae, Lampriminae, Lucaninae, and Syndesinae, and this classification continues in general to be followed by recent workers (D’Hotman & Scholtz 1990; Nel & Scholtz 1990). Howden & Lawrence (1974) increased the number to 5 by establishing Nicaginae to contain Nicagus Leconte and Ceratognathus Westwood, which I had treated as aesalines. I do not think the differences they have emphasised warrant the creation of a separate subfamily and until a more detailed study has been made of all the genera involved I prefer to treat Nicagus and Ceratognathus as aesalines (Holloway 1998). A separate subfamily, Penichrolucaninae, was proposed by Arrow (1950) for the few species of Penichrolucanus Deyrolle, 1863 but it is likely that this mainly tropical genus belongs in Lucaninae.
Together the 3 subfamilies Aesalinae, Lampriminae, and Syndesinae comprise only about 100 species compared with the approximately 1200 species in Lucaninae. As a group the 3 subfamilies are easily separated from Lucaninae by their partially or non-geniculate antennae (compared with the geniculate antennae of Lucaninae), their entire (undivided) eyes (rather than the partially or completely divided eyes of Lucaninae), the apical (rather than basal or central) position of the labium on the mentum, the highly unusual sclerotised prementum that looks superficially like a segment of the labial palp, (compared with the “normal” membranous prementum of Lucaninae) (see Fig. 7–12), and the eversible internal sac (rather than a permanently everted internal sac) of the male genitalia. Howden & Lawrence (1974) consider the eyes of Aesalus Fabricius not to be entire, but the structure they interpret as a canthus is not actually joined to the eye, instead it merely overlies it (see Holloway 1969 for a discussion on the canthus).
The conspicuous sexual dimorphism and allometry that are features of many stag beetles especially those in Lucaninae have created problems in delimiting species. At the generic level difficulties are likely to arise because of convergence, very similar external features being conspicuously present in otherwise completely different and unrelated lucanids. The group with which I am especially familiar in this category is the Serrognathus complex. In the process of identifying S. sika (Kriesche) for this revision I was able to examine a small range of species, all of which are currently placed either in Serrognathus Motschulsky or in Dorcus MacLeay. Externally they share a number of prominent features. They are large, rather flattened, shiny, black lucanids with very broad rectangular heads and broad rectangular pronota, and the males all have long, somewhat similarly dentate mandibles, but a study of both the male and the female genitalia and a subsequent detailed examination of less conspicuous external structures (mentum, antenna, 5th ventrite) has indicated that 5 different genera are represented in this group of species (see section on Serrognathus in this volume). The configurations of both the male and the female genitalia provide the most reliable features for distinguishing genera throughout Lucanidae (e.g., see fig. 22–38 in Holloway 1998). Having grouped specimens according to these configurations it is easy to find additional generic characters on external parts of the body. Considering the present uncertainties about limits of genera and subfamilies in Lucanidae the category “tribe” seems to me to be meaningless and misleading, and I do not use it.